The Bug Theater has always maintained an eclectic national profile, but on Thursday, March 23, it will concentrate on a disparate bill of excellent local acts, including Ratiocination, Some Gumption, Mystery Children and Judith Priest. It's a sensibility, not a sound, that ties these groups together, as all four focus on mood and group interaction rather than on solos and lead roles. As Judith Priest, poet Robert Rutherford and musical guests take an approach that differs from most poetry readings (or "ego stroking...cries for help," as he calls them): Rutherford largely improvises alongside whomever is working with him (a drummer, in Thursday's case). The primary concern of the trio Some Gumption is to create an aura reminiscent of the more intimate moments of the Velvet Underground. None of the players seem comfortable taking over vocal duties, however, which actually lends a good deal of their charm. Mystery Children, formed by Conrad Kehn (last seen fronting Skull Flux), comes described as "free rock," wherein Kehn works turntables and keyboards while the rest of the rotating membership of the band (which can include as many as nine people, some of whom have never met before, playing on stage together) improvises from the snatches they're given. Ratiocination, a hip-hop/funk group formed last summer by Chip Brokaw, will close the show. It's grown from a trio to its current septet and, as Brokaw states, "we try to always have guests." That fact -- along with the sax, tuba, guitar, bass, drums and two vocalists that are part of the regular unit -- should make for a full night of bugged-out sound.